The invention disclosed herein relates to devices that assist in the rolling and unrolling, or winding and unwinding, of flexible coverings, or increases the safe operation of such flexible coverings, for opening in a building, e.g., rollup doors to cover a doorway. The invention has application, or potential application, to the construction or building fields, e.g., rollup coverings for doorways, windows, or other openings in structures or buildings, as well as in the transportation field, e.g., ships, railcars, aircraft, commercial vehicles, or other fields in which a flexible rollup covering is desirable.
Industrial facilities, such as factories, warehouses, garages, and the like, may use rollup doors to cover doorways or other areas to separate the interior of the facility from the exterior, to separate areas within the facility in order to provide security, as well as protection from noise, debris, and unwanted climactic variations. Typical rollup door systems include a rollup door and a drum positioned above the doorway to be covered, and a drive motor or system for powering the rotation of the drum. Some door systems are capable of moving quickly between a closed position, in which the door is unwound from the drum and covers the doorway, and an open position in which the door is wound upon the drum and the doorway is uncovered.
Large rollup doors, or those which open or close quickly, are often equipped with a counterbalance system to counteract the force applied to the drum attributable to the weigh of the portion of the rollup door not wound upon the drum. Counterbalance systems may also be provided to ensure the safe operation of a flexible covering and to enable manual operation of the covering, for example, during a power interruption or drive failure.